JP3301035B2 - Method for producing glass composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a glass composition, and more particularly to a method for producing a glass composition exhibiting a laser or optical amplification effect used for optical measurement, optical processing, optical communication and the like. is there.

[0002]

2. Description of the ^Related Art As an application example utilizing the stimulated emission of Cr ⁴⁺ ions, single crystal lasers such as YAG or Y ₂ SiO ₅ and Mg ₂ SiO ₄ are known. The lattice contains Cr ions.

[0003] The inclusion of Cr ions in glass has been attempted in many glass types so far, but the contained C
Most of the r ion species are Cr ³⁺ or Cr ⁶⁺ .

[0004]

In the above-mentioned prior art,
The Cr ions doped in the glass, like other ions, fit into various ligand fields in the glass and form a valence state according to the ligand field, but the Cr ⁴⁺ ions are chemically Is extremely low, so that Cr ³⁺ or Cr ⁶⁺
Since it is converted into ions, there is a problem that it is extremely difficult to generate it as Cr ⁴⁺ ions.

An object of the present invention is to provide a laser in which the wavelength range exhibiting laser oscillation or optical amplification is remarkably wide, and the center wavelength of which is 1.3 to 1.5 μm which is important for the optical communication wavelength range. Another object is to provide a method for producing a glass composition that can be used for an optical amplifier.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0007]

In order to achieve the above object, a method for producing a glass composition for optical amplification according to the present invention comprises a method for producing a divalent ion selected from beryllium, magnesium, calcium, strontium and barium. Alkaline earth oxide is used for the main composition, and trivalent and tetravalent ion oxides are introduced into the main composition. The chromium tetravalent charge-compensated glass contains Cr ions of various valences to melt the glass. Oxygen concentration used as atmosphere is 0.001 to 0.01
Was adjusted to%, some oxygen, He, Ne, Ar, Kr
^{Alternatively} , Cr ⁴⁺ ions are produced in the glass by controlling the oxidation-reduction equilibrium by a mixed gas with Xe .

The Cr ⁴⁺ ion-doped glass produced by this method produces strong fluorescence in a wide wavelength band of 1.1 to 1.7 μm shown in FIG. 1, and if this is used as an optical amplifier, Optical amplification with a wider wavelength range than before has been possible. FIG. 1 shows an emission spectrum of a glass composition of Sample No. 18 of one embodiment of the present invention, which is excited by a YAG laser of 1.06 μm.

Hereinafter, the present invention will be described in detail. The basic production method of the present invention is to add an alkaline earth oxide (BeO, MgO, CaO, SrO, BaO) to a glass composition in a range of 10 to 10.
It is to produce a Cr ⁴⁺ ion-doped glass by containing 72 mol (mol)% and strictly controlling the atmosphere gas composition at the time of producing the glass.

When the content of the alkaline earth oxide is less than 10 mol%, the fluorescence intensity is significantly reduced. Further, when the alkaline earth oxide content is 72 mol% or more, problems such as difficulty in vitrification are caused. The content of Cr ions is 10 to 10000 ppm by weight, and the optimal addition amount range is 20 ppm.
0 to 1000 ppm. If the Cr ion content is less than this range, the effect of the addition is not obtained, while if it exceeds the above range, the effect of the addition is reduced.

The basic glass compositions are B ₂ O ₃ , P ₂ O ₅ , V ₂ O ₅ , As ₂ O ₅ , Sb ₂ O ₅ having glass forming ability and monovalent glass components Li ₂ O, Na _2. O, K ₂ O, Rb ₂ O and Cs ₂ O are not contained at all. However, in order to stabilize the glass, the content of SiO ₂ , GeO ₂ , and SnO ₂ is from 0 to 50 mol%. That is, 0 expressed by the following equation 1 in mol%
It is a glass composition having a content of ５０50 mol%, preferably 5-15 mol%.

[0012]

## EQU1 ## [SiO ₂ + GeO ₂ + SnO ₂ ]: 0 to 50 mol%
(Preferably 5 to 15 mol%) Here, the mol% of the whole components is shown in the symbol [].

Other glass compositions are mainly BeO, Mg
It is composed of divalent, trivalent, tetravalent, and pentavalent oxides, which are glass components that contribute to stabilization of alkaline earth oxides such as O, CaO, SrO, and BaO. The mol% of the whole component is a glass composition represented by Formula 2, Formula 3, Formula 4, Formula 5, or Formula 6.

[0014]

[Al ₂ O ₃ + Ga ₂ O ₃ + In ₂ O ₃ ]: 0 to 60 mol% (preferably 5 to 25 mol%)

[0015]

## EQU3 ## [ZnO + CdO + PbO]: 0 to 40 mol%
(Preferably 15 to 25 mol%)

[0016]

[Sc ₂ O ₃ + Y ₂ O ₃ + La ₂ O ₃ ]: 0 to 40 mol% (preferably 5 to 20 mol%)

[0017]

## EQU5 ## [TiO ₂ + ZrO ₂ ]: 0 to 40 mol% (preferably 10 to 20 mol%)

[0018]

## EQU6 ## [Ta ₂ O ₅ + Nb ₂ O ₅ ]: 0 to 40 mol% (preferably 10 to 20 mol%) These glass compositions can be roughly classified into the following five from the viewpoint of the constitutional composition.

The first group is a glass composition in which trivalent ions such as aluminum oxide, gallium oxide, and indium oxide are introduced into a glass composition containing magnesium oxide and calcium oxide as main components. This composition is characterized by the use of alkaline earth ions such as Ca ²⁺ and Mg ^2+.
Metallic C that compensates for electrification of the valent chromium ions
r or Cr ions of each valence are generated as Cr ⁴⁺ ions, and this active ion provides a broadband light amplification effect described later. In this glass system, Cr
^{The 4+} ion increases with an increase in the composition of the alkaline earth oxide. In particular, when the composition of calcium oxide and magnesium oxide is 50 mol% or more, the tendency becomes more remarkable.

That is, the glass composition of the present invention comprises:
By replacing a part of O with other divalent ions (BeO, SrO, BaO), or adding trivalent or pentavalent ions, the thermal properties such as glass transition temperature and melting point can be adjusted. Formation can be achieved.

Further, by substituting a part of Al ₂ O ₃ with another trivalent ion, it is possible to adjust the same thermal characteristics as the effect of adding the divalent ion. On the other hand, part of CaO
Substitution with O can significantly lower the melting point of the glass.

The second group is a glass composition in which trivalent ions such as scandium oxide, yttrium oxide, and lanthanum oxide are introduced into a glass composition mainly composed of magnesium oxide and calcium oxide. This composition is characterized by a higher concentration of C than the first glass composition.
r ⁴⁺ ions can be generated, and as a result, the emission intensity is further increased. FIG. 1 shows the emission spectrum of this glass composition. The formation of Cr ⁴⁺ ions in this composition is probably due to the alkaline earth oxide Be ²⁺ ,
It is considered that divalent ions such as Mg ²⁺ and Ca ²⁺ and trivalent ions such as Y ³⁺ and La ³⁺ are effectively acting on charge compensation of Cr ⁴⁺ ions. In any case, this glass composition has a broad band due to the effect of Cr ⁴⁺ active ions,
In addition, a high-intensity light-emitting characteristic is obtained. If an optical amplifier is formed using this glass, an amplification characteristic higher than that of the first glass composition can be expected.

This glass composition has a melting temperature of 50 to 200 ° C. higher than that of the first group, but also in this glass system, similarly to the first group, divalent, trivalent, By substituting a part of the composition with tetravalent and pentavalent ions, it is possible to stabilize the glass and control the thermal characteristics.

The third group is a composition comprising calcium oxide and magnesium oxide and SnO ₂ or PbO. A compositional feature of this glass is that the glass can be formed without containing aluminum oxide. Also in this glass system, a broadband fluorescence characteristic can be obtained as in the first group. In addition, bivalent, trivalent, 4
By substituting a part of the composition with pentavalent and pentavalent ions, the stabilization and thermal properties of the glass can be controlled.

The fourth group is a composition comprising calcium oxide and magnesium oxide and titanium oxide or zirconium oxide. The compositional feature of this glass is that the glass can be formed without containing aluminum oxide. In this glass system, as in the first group, stabilization and thermal properties of the glass can be controlled by partially substituting the composition with divalent, trivalent, tetravalent or pentavalent ions.

The fifth group is a composition comprising calcium oxide and magnesium oxide and niobium oxide or tantalum oxide. The compositional feature of this glass is that the glass can be formed without containing aluminum oxide. In this glass system, as in the first group, stabilization and thermal properties of the glass can be controlled by partially substituting the composition with divalent, trivalent, tetravalent or pentavalent ions.

[0027] (chromium-doped type) Table 1, as chromium-doped species contained in the glass compositions in Table 3 and Table 4, metallic chromium and chromium oxide _{(CrO, Cr 2 O 3,} CrO 2,
CrO ₃ ), chromium sulfide (Cr ₂ (SO ₄ ) ₃ .nH)
₂ O), chromium chloride _{(CrCl 3 · 6H 2 O)} , chromium nitrate _{(Cr (NO 3) 3 ·} 9H 2 O) and chromium hydroxide (Cr
(OH) ₃ .nH ₂ O) was used. The doped Cr ion takes a valence state corresponding to various sites in the glass. However, when the glass compositions shown in Tables 1, 3 and 4 of the glass composition table are used, all the chromium dopant materials have a degree of valence. Despite the difference, it was confirmed that fluorescence was obtained in a wide wavelength band of 1.1 to 1.7 μm by Cr ⁴⁺ active ions.
In particular, metallic chromium and chromium oxides (CrO, Cr
Large fluorescence intensity was obtained in the glass used ₂ O _3, CrO _2, a CrO ₃₎ as a dopant.

The above-described glass composed of the glass composition and the Cr dopant material shows a fluorescence spectrum similar to that of FIG. 1 when the Cr ion concentration is 10 ppm or more. 2-1.7 μm
The laser oscillation was confirmed in the wavelength range of the range.

[0029] The state of the Cr ions in said glass is by analogy with the results of the fluorescence characteristics of the Cr ion-doped YAG crystal, Cr ⁴⁺ tetrahedron 4 to be involved in fluorescence properties
It has a coordination structure, and its bonding state is an oxide of CrO ₂ alone,
Alternatively, it is considered that a composite oxide of a CrO ₂ oxide and an alkaline earth oxide or yttrium, lanthanum, or the like is formed, and all exist as microcrystals having a nanometer (nm) size.

As described above, the formation of Cr ⁴⁺ ions depends on the composition of alkaline earth oxides, yttrium, lanthanum, and other oxides which strongly affect the formation of tetravalent ligand fields, and the composition of the atmosphere gas during glass production. Depends heavily.

In the method for producing the glass composition for laser or optical amplification according to the present invention, a melting method is used for the glass production method, and the melting temperature varies depending on the glass composition.
To 1600 ° C and in a melting atmosphere, 0.00
Oxygen, He, Ne, A , adjusted to 1-0.01%
A mixed gas of r, Kr or Xe is used, and the melting atmosphere is adjusted to a desired oxidizing and reducing atmosphere and the valence of Cr ions is controlled by the combination of the mixing ratio of the atmospheric gas and the gas type.

Further, after cooling the molten glass to room temperature in the atmosphere or the above-mentioned inert gas,
C. for 10 hours or more, and then slowly cooled to room temperature at a cooling rate of 0.5 to 2 ° C./min. As the atmosphere gas, an inert gas such as He, Ne, Ar, Kr, or Xe, and O ₂ , H ₂ ,
A gas mixture of at least one of CO and CO ₂ gases is used.

By adjusting the atmosphere gas composition, the Cr ⁴⁺ ions generated during the melt synthesis can be stably and easily stored in the glass.

Although the glass composition produced by the above-described production method exhibits a laser or optical amplification action in a bulk form, the same applies to an optical waveguide or an optical fiber in which a region centered on a core is doped with Cr ions. The effect was shown. As a manufacturing method, a conventional method can be applied. For example, as an optical fiber manufacturing method, a rod-in-tube method or a method of drawing the glass composition of the present invention into a glass tube of the present composition containing no quartz glass and Cr and drawing the same can be applied.

[0035]

According to the method for producing a glass composition of the present invention, inexpensive calcium oxide is used as the main glass composition, and Cr ⁴⁺ ions are formed by an easy method such as controlling the atmosphere gas composition during glass melting and subsequent heat treatment. Can be synthesized, which is a very advantageous feature in glass production. Furthermore, in this manufacturing method, the synthesized Cr ⁴⁺ ion does not largely depend on the chemical bonding state of the dopant material or the valence of the dopant material, so that there is a feature that various kinds of dopant materials can be applied. Moreover, even after forming the element from the melted glass or fabricating the fiber, it is possible to adjust the ion valence to a desired value by performing the same treatment as the heat treatment after the melting.

[0036]

Embodiments of the present invention will be described below in detail. Examples of the glass composition for an optical amplifier of the present invention are shown in Tables 1, 3 and 4.

(Embodiment 1) In Embodiment 1 according to the present invention,
The glass composition (mol%) shown in Table 1 was synthesized by the following method. First, a carbonate or oxide as a glass material is thoroughly mixed in an agate mortar, and a predetermined amount is put into a platinum crucible, and He gas or oxygen is added so that the oxygen concentration becomes 0.01%. The temperature was raised from room temperature at a rate of 2 ° C./min to 20 ° C./min in an atmosphere furnace made of a mixed gas with He, and kept at 1000 ° C. for 1 hour to degas moisture and adsorbed oxygen in the glass raw material. After that, 2 ℃ / min ～ 20 ℃ / m
Heating control to 1400-1600 ° C at a heating rate of in,
The mixture was held at the same temperature for 30 to 90 minutes for melt synthesis.

The glass synthesized by melting is 600 to 850 ° C.
After the glass melt is poured onto the preheated mold and naturally cooled to room temperature, at least one of an inert gas such as He, Ne, Ar, Kr, and Xe and an O ₂ , H ₂ , CO, or CO ₂ gas is used. In an electric furnace in an inert atmosphere (argon gas, nitrogen gas, helium gas, etc.) using a mixed gas with a seed gas, the temperature is maintained at 750 ° C. for 10 hours, and 0.5 ° C./min to 2 ° C./min
At room temperature. Slowly cooled glass is 10mm
× 20mm × 2 ^tmm cut into a plate shape, cut surface 40
Polishing was performed up to No. 00.

In the fluorescence measurement of glass, the oscillation wavelength was 1.06.
When a wavelength range from 1100 nm to 1700 nm was measured with a spectroscopic optical system using cooled Ge as a detector using a μm YAG laser beam as excitation light, a fluorescence spectrum similar to that in FIG. 1 was obtained. Table 2 shows the results of the fluorescence measurement of this glass system.
Shown in As Table 2 shows, the fluorescence intensity was calcium oxide,
It can be seen that it largely depends on the magnesium oxide composition and the oxygen concentration in the melting atmosphere.

The fiber was prepared by a rod-in-tube method, using a quartz glass tube or glass of sample No. 8 not doped with Cr as a clad glass, and inserting a glass composition shown in Table 1 as a core glass into a silica-based fiber. Drawing was performed by a drawing apparatus.

Glass composition: The glass composition shown in Table 1 was directly lined with 2 m
m, cut to a length of 20 mm, polished the end face, center wavelength 1.
It was fixed in a laser resonator with a 4 μm narrow band filter. YAG laser light of 1.06 μm from one side is applied to 200
When mw was incident, an output of 100 mw was obtained. At this time, the oscillation wavelength was 1.4 μm and the line width was 0.01 μm or less. As described above, the glass compositions shown in Table 1 are useful as laser or optical amplification matrices. In this glass system, the laser oscillation efficiency is improved by increasing the composition of calcium oxide and magnesium oxide and controlling the oxygen concentration in the melting atmosphere, as in the case of the above-mentioned fluorescent characteristics, and the calcium oxide composition is 50 mol% and the magnesium oxide is 3 mol% or more. Oxygen and H adjusted to an oxygen concentration of 0.01 to 0.001% as an atmosphere gas at the time of glass production.
The use of a mixed gas of e, Ne, Ar, Kr or Xe significantly increased the oscillation efficiency.

The fluorescence and laser characteristics described above vary greatly depending on the glass composition and the atmosphere gas composition.
This is because the content of Cr ⁴⁺ ions that become active ions greatly varies depending on the glass composition and the atmosphere gas composition. According to the method for producing a composition for laser and optical amplification of the present invention, Cr ^{4 is} obtained by using an alkaline earth oxide as the main composition in the glass composition and precisely controlling the oxygen concentration in the atmosphere gas. ⁺ Ion generation reaction was promoted.

Example 2 The glass composition (mol%) shown in Table 3 was synthesized in the same manner as in Example 1. This glass system is a glass composition obtained by adding the Y ₂ O ₃ and La ₂ O ₃ compositions to the compositions shown in Table 1. FIG. 1 shows a typical fluorescence spectrum of this glass composition. In this glass system, an increase in the fluorescence intensity was achieved by increasing the yttrium oxide and lanthanum oxide compositions and by combining the optimum atmosphere gas compositions. In particular, when the glass composition has a yttrium oxide composition of 5 mol% or more and a lanthanum oxide composition of 7 mol% or more, the oxygen concentration of the atmosphere gas is 0.0%.
In the range of 1 to 0.001%, the fluorescence intensity increased remarkably. Also in this glass composition, a fiber was formed by the method of Example 1 and a laser characteristic having the same oscillation efficiency as that of Example 1 was obtained.

The increase in the fluorescence intensity with the increase in the yttrium oxide and lanthanum oxide compositions in the glass compositions in Table 3 is due to the increase in Cr ⁴⁺ ions in the glass. That is, in addition to the alkaline earth ions, yttrium and lanthanum ions are also effective as charge compensation ions of Cr ⁴⁺ ions. That is, in this glass system, the composition range for controlling Cr ⁴⁺ ions is significantly widened, and a higher concentration of Cr ⁴⁺ ions can be generated.

Also in this glass system, the fluorescence intensity greatly depends on the oxygen concentration of the atmospheric gas, and the oxygen concentration is 0.0
In the range of 0.01 to 0.01%, the fluorescence intensity increases remarkably, but when it exceeds this range, it decreases sharply. This is because the concentration of Cr ⁴⁺ ions generated in the glass increases or decreases ^{depending on} the oxygen concentration in the atmospheric gas. In any case, in the case of this glass composition, the fluorescence spectrum shown in FIG. 1 was obtained as in the case of the glass composition in Table 1. That is, as in Example 1, by strictly controlling the oxygen concentration in the atmosphere gas, a glass having a wide band and high fluorescence intensity was obtained.

Example 3 The glass composition (mol%) shown in Table 4 was synthesized in the same manner as in Example 1. The feature of this glass system is that the calcium oxide composition is 30 mol% or less and no aluminum oxide is contained. Also in this composition, Table 1
As with the glass compositions of Table 3 and Table 3, the fluorescence spectrum shown in FIG. 1 was obtained. Also in this glass composition, a fiber was obtained by the method of Example 1 and a laser characteristic having the same oscillation characteristics and oscillation efficiency as in Example 1 was obtained.

Table 4 shows the measurement results of the fluorescence measurement when the Cr content of the glass composition of Sample No. 18 was changed.

The characteristics of this glass system are that the composition of calcium oxide is 30 mol% or less and no aluminum oxide is contained. Also in this composition, the fluorescence spectrum shown in FIG. 1 was obtained similarly to the glass compositions in Tables 1 and 3. Also in this glass composition, a fiber was formed by the method of Example 1 and a laser characteristic having the same oscillation characteristics and oscillation efficiency as in Example 1 was obtained.

Table 5 shows the measurement results of the fluorescence measurement when the Cr content of the glass composition of Sample No. 18 was changed.

By using the manufacturing method of the present invention, as shown in Table 5, a laser or an optical amplifier having Cr ⁴⁺ ions as an active center can be formed with all the above glass compositions.

As described above, the present invention has been specifically described based on the embodiments. However, it is needless to say that the present invention is not limited to the above-described embodiments and can be variously modified without departing from the gist thereof.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

[0056]

[Table 5]

[0057]

As described above, if a laser or an optical amplifier using the glass composition of the present invention is constituted,
An unprecedented breakthrough laser or optical amplifier that can cover the entire practical communication wavelength range including 1.3 to 1.5 μm, which is the most important in optical communication, is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an emission spectrum of a glass composition of Sample No. 18 of one example of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H01S 3/17 H01S 3/17 (72) Inventor Tadashi Sakamoto Nippon Telegraph and Telephone Corporation, 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo (56) References JP-A-6-296058 (JP, A) JP-A-4-219345 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 3/00 C03C 3 / 062 C03C 3/12 C03C 4/12 C03B 5/16 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. BeO, MgO, CaO, S in a crucible
and rO, and alkaline earth oxides of at least one of BaO comprise 10 mol% to 72 mol%, and, placing a chromium-doped glass raw material containing a glass raw material and chromium-doped type, wherein the chromium-doped glass Heating process for heating and melting raw materials
When a method of manufacturing a <br/> glass composition and a step of rapidly cooling the chromium-doped glass material, the heating step, the oxygen concentration is 0.001% to 0.01%
Adjusted oxygen and He, Ne, Ar, Kr or
A method for producing a glass composition, which is carried out in a melting atmosphere comprising a mixed gas with Xe . Wherein said chromium-doped species, metallic chromium, chromium oxide, chromium sulfide, wherein the chromium chloride is at least one selected from among chromium nitrate, and chromium hydroxide A method for producing the glass composition according to claim 1.